Those skilled in the art understand the challenges associated with the operation of batteries (of all types and chemistries). Typical problems associated with the use of batteries, which the present invention addresses are:                Determination of accurate state of charge        Prediction and Detection of battery failure        Unbalanced capacity within a plurality of cells or batteries within a battery pack        Information collection and storage within a battery pack        Battery module to battery module isolated data collection and equalization        Control feedback from battery pack to bulk charger        
Typically the battery management system (BMS) is physically located on the battery pack in order to measure a variety of parameters relating to charging the battery, which may be a motor vehicle battery or a battery for operating machinery, such as fork lifts, and product transportation vehicles.
Such information communicated to a battery charger includes, but is not limited to, current flow in or out, voltages and temperature of one or more batteries or cells within a battery pack.
A difficulty with the typical method of communication between the battery charger and the battery management system (BMS) is that an additional connection is required. Typically a dedicated conductor pair is used to communicate from the battery charger to the battery management system (BMS). Typically only a two-wire connector is required to charge a battery pack, specifically for the positive and negative terminal. The challenge that is presented with the addition of more conductors is that a connector having multiple contacts is required. This addition of hardware adds cost and complexity to the system, since multiple pin connectors are more expensive and more labor intensive to install or maintain.
Moreover, Echelon Systems Corporation of Los Gatos Calif. has developed bi-directional interconnectable sensing and communications chips for communication of message packets of intelligent information cells, which are useful in battery charging management. Among these patents include U.S. Pat. Nos. 4,918,690, 4,941,143, 4,955,018, 4,969,147, 5,297,143, 5,319,641, 5,420,572, 5,500,852, 5,513,324 and 5,519,878.